Here are two things from the shop: a bag of sugar with 1 kg written on the label, and a bag of flour with 1,000 g written on the label. Hands up: which one is heavier, the sugar or the flour? Or are they somehow the same?

The interactive shows a conversion ladder for weights between kilograms and grams. Look at how the digits sit across the columns on each card. Notice which way we multiply and which way we divide.

First we work one rename all the way through on the board:

1,500 g → kg and g

• Grams to kilograms is a bigger unit, so we divide by 1,000.
• 1,500 ÷ 1,000 gives 1 full kilogram.
• 500 g are left over, not enough for another kilogram.
• So 1,500 g = 1 kg 500 g.

Then we watch the ladder with three more: 1 kg to grams, 2 kg to grams, and the mixed unit 1 kg 200 g combined into grams.

Today we work through these weights together on the ladder: first 3 kg to grams, then 4,000 g back to kilograms, then 1 kg 200 g to grams, and finally 2,750 g to kilograms and grams. Before each one we will say whether we multiply or divide.

We work through four renamings on the board, and they get a step harder as we go. The first two are single steps: 4 kg to grams multiplies by 1,000, and 5,000 g to kilograms divides by 1,000. The last two ask for the answer in both units: 1,300 g and then 2,250 g, each written as a number of kilograms and the grams left over. Type the kilograms in the first box and the leftover grams in the second.